INTRODUCTION

Dermatophytoses are cutaneous diseases caused by filamentous fungi called dermatophytes, capable of invading and remaining in keratinized tissues, such as the stratum corneum of the skin, hair and nails; using keratin as their main source of energy ^1-4.

Currently these fungi belong to the family Arthrodermataceae, which includes 9 well defined phylogenetically and morphologically genera ⁵, within which Microsporum and Trichophyton are responsible for most of the infections described in pets and exotic animals, such as dogs, cats, rabbits, guinea pigs, ferrets and hedgehogs ^1-4,6-13. Those that live in a close relationship with human beings have a negative impact on their health, due to the risk of transmitting these fungi from an infected or colonized animal ^4,6,13.

Due to the increase in queries for exotic animals in veterinary clinics and the limited information that exists regarding the state of colonization by dermatophytes in rabbits, the objective of this study was to determine the presence of dermatophytes in clinically healthy rabbits from pet stores in the Northern area of the city of Santiago de Chile.

MATERIALS AND METHODS

Samples. In the period between October and December 2015, 42 samples were analyzed, from the skin surface of 42 rabbits (Oryctolagus cuniculus), kept inside metal cages, living (17) or not (25) with guinea pigs, from four Pet stores from the Northern sector of the city of Santiago de Chile.

Inclusion and exclusion criteria. Clinically healthy rabbits were chosen randomly, without differentiating between sex, race or age group. Animals with any underlying disease and presence of lesions on skin and / or hair coat were excluded.

Sampling. Before the sample was taken, a clinical examination of the rabbits was carried out, by visual inspection and palpation, recording background such as age, sex, breed, type of feeding and coexistence with other animals in a clinical record. Sampling was done by separating the hair of the animal, then rubbing the entire surface of the hair coat with a sterile dressing of 3x3 cm2 ¹¹. The samples were labeled and subsequently sown by printing on Sabouraud glucose agar (ASG, Oxoid^®) and Dermatophyte Test Medium (DTM, Himedia^®).

Culture and identification. Incubation was carried out at 25°C under aerobic conditions with a biweekly observation for 21 days. The cultures that presented growth morphologically coincident with dermatophytes were isolated and replicated in ASG. The identification of genus and species was made based on the characterization of the colony and microscopic morphology of the fruiting structures of the dermatophyte, using a previously described classification key ¹⁴.

RESULTS

Of the 42 sampled rabbits (34 females and 8 males), three (7.1%) presented colonization by dermatophytes. Of these, two were isolated from male rabbits, while the other was recovered from a female.

The animals studied ranged in age from 3 to 6 months and were of the following breeds: rabbits with fallen ears, lion heads, and European rabbits. The three isolations were obtained from the lion head rabbits.

Regarding coexistence with guinea pigs, of the 17 rabbits that lived with them, two presented positive culture to dermatophytes, as shown in Table 1, showing a trend between coexistence and colonization by these fungi.

The dermatophyte species identified in the three cases was Trichophyton mentagrophytes. In ASG, the isolates of this species were characterized macroscopically, because they show flat, yellowish-cream colored colonies, slightly darker in the central area. The mycelium was pulverulent or granular. Microscopically, the most consistent feature was the production of globose microconidia arranged in grape clusters. The macroconidia were almost completely absent; they were thin with smooth walls, in the shape of a cigar with a narrow anchorage at the base and the presence of spiral hyphae.

DISCUSSION

Dermatophytoses are skin infections that affect a wide range of animals, including rabbits (Oryctolagus cuniculus), which have been progressively incorporated as pets; thus, increasing the risk of transmission of these infections to humans.

The rate of colonization by dermatophytes in rabbits observed in this study was similar to that reported by d’Ovidio and Santoro in Italy ⁴, who found 3.3% colonization when 455 rabbits were studied. However, it differs from the only study conducted in Chile where a frequency of 54.7% of dermatophytes was found in healthy rabbits, with M. canis being the only isolated species ¹⁵.

In this investigation, a trend was observed between the frequency of colonization by dermatophytes and coexistence with guinea pigs; agreeing with previous publications, ^4,10,11,18 it would be interesting to confirm this information with additional studies in the country, where a greater number of animals is included; given the probability of transmission of these fungi between animals when they are in direct contact, for example sharing the same cage.

The only isolated species in this study was T. mentagrophytes, which presented macro and micromorphological characteristics consistent with what was previously described ¹⁴. Different authors point to this species as the most frequent to isolate in rabbits ^{1-4,8,10,12,13}. However, they differ from that reported by Zaror et al., 1988 almost three decades ago in the Southern part of Chile; where M. canis was identified in all the samples analyzed, obtained from the hair mantle of Angora rabbits ¹⁵.

According to the results of this research, maintain a cleaning and disinfection protocol, perform clinical and mycological surveillance and separate carrier animals from those that are not; would help reduce the possibility of dermatophyte transmission between individuals.